Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/20—Closing valves mechanically, e.g. arrangements of springs or weights or permanent magnets; Damping of valve lift
  • F02M61/205—Means specially adapted for varying the spring tension or assisting the spring force to close the injection-valve, e.g. with damping of valve lift
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
  • F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
  • F02M45/10—Other injectors with multiple-part delivery, e.g. with vibrating valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/04—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series
  • F02M61/08—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series the valves opening in direction of fuel flow
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/161—Means for adjusting injection-valve lift
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
  • F02M2200/21—Fuel-injection apparatus with piezoelectric or magnetostrictive elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
  • F02M2200/30—Fuel-injection apparatus having mechanical parts, the movement of which is damped
  • F02M2200/304—Fuel-injection apparatus having mechanical parts, the movement of which is damped using hydraulic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/167—Means for compensating clearance or thermal expansion

Definitions

• the present invention relates to a fuel injector for an internal combustion engine, especially diesel, intended in particular to be implemented in a motor vehicle.
• a conventional internal combustion engine comprises at least one cylinder in which a piston slides between two extreme positions.
• the piston defines with the cylinder and a cylinder head a combustion chamber.
• an injector has the function of supplying finely pulverized fuel to the combustion chamber of the internal combustion engine.
• An injector 10 is already known, as shown in FIG. 1, making it possible to perform injections at ultrasonic frequencies.
• This injector 10 comprises an injector body 12, intended to be fixed to the upper end of the engine cylinder head by means not shown, which terminates in its lower part by a nozzle 14 and which has a first internal cavity 16 and a second upper cavity 18.
• the first inner cavity 16 is intended to be filled with pressurized fuel. To do this, the first cavity 16 is connected to a fuel supply port 20 adapted to be placed in communication with a pressurized fuel supply circuit (not shown).
• the first cavity 16 opens at the lower end 22 of the nozzle 14, also called the nose of the injector, by an injection orifice 23.
• the injector 10 also comprises a rod 24, or needle, extending mainly according to the Y-Y 'axis.
• the rod 24 is housed axially movable inside the nozzle 14.
• the lower end of the rod 24 has a closure head 26 extending in part outside the nozzle 14.
• This sealing head 26 is adapted to come into contact with the inner surface of the nozzle 14 delimiting the injection orifice of the nozzle 14 so as to close off the fuel injection orifice.
• an active assembly 28 shown partially broken away in FIG. 1, which is supplied with current by means of electric cables 29.
• the active assembly 28 comprises in this case a magnetostrictive rod 34, mounted integral with the rod 24, in the extension thereof, a solenoid 36 mounted wound around the magnetostrictive rod 34, a mass 38 and a spring 40 of prestressing of magnetostrictive bar 34, the prestressing spring 40 being mounted between a plug 42, which closes the end of the housing 44 of the active assembly 28 opposite the rod 24, and the mass 38.
• the magnetostrictive bar 34 is deformed in compression.
• the housing 44 of the active assembly 28 is mounted to move in axial translation along the axis YY 'in the second cavity 18 formed in the injector body 12.
• the housing 44 is however elastically connected by a holding spring 30 to the body 12 of the injector 10.
• the system 31 consisting of the active assembly 28 and the retaining spring 30 is housed in the second cavity 18 formed in the rear part of the body 12 of the injector 10.
• An exhaust duct 32 formed in a plug 33 closing the injector body 12 makes it possible to evacuate the fuel at low pressure present in the second cavity 18 which comes from small leaks between the first cavity 16 and the second cavity 18.
• the rod 24 is able to slide and / or to deform axially relative to the housing 44 of the active assembly 28.
• the walls of the housing 44 have a certain elasticity. This elasticity can also be provided by an elastic washer acting on the shoulder 45 of the rod 24.
• the mass 38 is fixed in bearing on the magnetostrictive bar 34 so as to achieve a mechanical impedance break at the interface between the magnetostrictive bar 34 and the mass 38.
• the preload applied makes it possible, on the one hand, to seal the injection orifice formed at the end of the nozzle 14 when the injector 10 is supplied with fuel with a given pressure and, on the other hand, to catch up. possible wear in the contact zone of the closure head 26 of the rod 24 with the nozzle 14 and / or the differential expansion catch-up between the rod 24 and the injector body 12.
• Solenoid 36 when not supplied with current, does not generate a magnetic field.
• the magnetostrictive rod 34 is not elongated and the holding spring 30 acting on the housing 44 plates the closure head 26 on its seat so as to close the injection orifice of the injector 10.
• the solenoid 36 When the solenoid 36 is supplied with current, for example by a current 46 (see FIG. 2), it generates a magnetic field that lengthens the magnetostrictive bar 34.
• the rod 24 is thus set in motion at its upper end and prints a movement at its lower end formed by the closure head 26.
• the displacement of the closure head 26 of the rod 24 can be amplified, in particular if the length of the rod 24 is chosen to acoustically tune the rod 24 to the ultrasonic excitation frequency.
• control current 46 corresponds, as shown in FIG. 2, to the superposition of a DC component 48 and of an AC component 50, for example a sinusoidal component (see FIG. 2).
• the elongation of the magnetostrictive rod 34 also contains a DC component and an AC component at the frequency of the AC component 50 of the control current 46.
• the displacements of the closure head 26 of the rod 24 therefore also contain a DC component and an AC component.
• the continuous component of the displacements of the closure head 26 of the rod 24 allows the lifting of the closure head 26 in a so-called "raised” position around which the alternating component makes it oscillate.
• the AC component whose frequency is generally of the order of a few tens of kilohertz, mechanically splits the fuel ply so that the fuel is sprayed into fine droplets in the combustion chamber.
• the lifting of the closure head 26 of the rod 24 relative to the seat therefore determines the average opening of the injector and therefore the average injection rate.
• such an injector 10 allows reduced injection and / or unreliable sealing.
• Injectors are also known where the vibrating of the rod is carried out indirectly by vibrating the nozzle by means in particular of piezoelectric ceramic elements mounted prestressed on the nozzle of the injector body.
• An object of the invention is therefore to provide a fuel injector for an internal combustion engine, in particular diesel, intended in particular to be implemented in a motor vehicle, does not have the aforementioned drawbacks, and in particular to benefit from the component continuous control current of the active element while ensuring a good seal of the injector.
• an injector body forming in particular a nozzle terminated by an injection orifice; means for closing off the injection orifice of the injector body, the closure means comprising an assembly carrying a vibrating rod; terminated at one end by a closure head of the injection port,
• the injector according to the invention it is possible, with the injector according to the invention, to block the movement of the assembly carrying the rod due to the means of reminder in the closed position, this to benefit from the continuous component of the lifting of the closure head of its seat during the injection phase.
• the return means in the closed position allow a slower movement of the assembly carrying the rod so as to compensate for differential thermal expansion phenomena. It is thus possible to choose the return means so that they exert sufficient force to ensure a good seal of the injector outside the injection phases, without having to achieve the compromise mentioned above.
• the injector according to the invention has one or more of the following characteristics taken alone or in combination:
• the locking means of the assembly carrying the rod relative to the body of the injector comprises a piston slidably mounted in a cylinder, the piston and the cylinder defining a first blocking chamber to be filled by a viscous liquid, the piston and the cylinder being one fixed with respect to the injector body and the other fixed with respect to the assembly carrying the rod;
• control means are of one of the types comprising the passive type and the active type;
• said first duct is produced by means of an adjusted machining of said piston with respect to said cavity;
• control means comprise a first duct of small passage section which puts in fluid communication the first blocking chamber with a cavity formed in the body of the injector and intended to contain low pressure fuel coming from leaks;
• the control means further comprises a second conduit which puts the first blocking chamber in fluid communication with the outside of the injector;
• the injector comprises means for closing the first conduit and / or means for closing off the second conduit and means for controlling the means for closing the first conduit and / or means for controlling the sealing means of the first conduit; second conduit;
• the locking means further comprises a second locking chamber, defined by the piston, opposite in the cylinder to the first locking chamber relative to the piston, the second chamber of blocking being intended to be filled with hydraulic fluid; the second blocking chamber is in fluid communication with the first blocking chamber by means of an exchange conduit, formed in the piston, of small passage section;
• the second blocking chamber is in fluid communication with the cavity formed in the body of the injector;
• the cylinder comprises a recess inside which a projection of the piston is able to slide in a sealed manner, the projection and the recess defining a third chamber which is in fluid communication with the cavity;
• the piston further comprises a projection extending to the outside of the injector, an axial channel being formed in this projection, which is in fluid communication with the first or second blocking chamber, which is closed at its end adjacent to the outer face of the injector and which has in its interior a movable plug, the space between this cap and the closed end the channel being filled with air; the first blocking chamber and, if appropriate, the second blocking chamber are filled with fuel-soluble grease;
• the first blocking chamber and, if appropriate, the second blocking chamber are filled with fat insoluble in fuel;
• the first blocking chamber and, if appropriate, the second blocking chamber are filled with fuel
• the assembly carrying the rod comprises an active device comprising in particular in a housing integral with the rod, the vibrating means of the rod;
• the vibrating means of the rod comprises a stack of elements able to deform so as to deform the nozzle of the injector, the assembly carrying the rod being constituted by a mass.
• FIG. 1 is a longitudinal sectional view of a known fuel injector active element magnetostrictive type
• FIG. 2 is a schematic representation of the control current of the active assembly in the injection phase
• FIG. 3 is a longitudinal sectional view of a fuel injector according to a first embodiment of the invention
• FIG. 4 is a longitudinal sectional view of a fuel injector according to a second embodiment of the invention
• FIG. 5 is an enlarged partial longitudinal sectional view of a detail of an injector according to a third embodiment.
• Embodiment of the invention, Figures 6 to 10 are views similar to Figure 5 showing a detail of an injector according to different embodiments of the invention.
• FIG. 3 shows an injector 52 according to a first embodiment of the invention.
• the injector 52 is of the outgoing needle head type.
• the elements of the injector 52 according to the first embodiment of the invention identical to the elements of the injector 10 shown in Figure 1 will not be described in more detail below.
• the injector 52 according to the first embodiment of the invention is remarkable in that it comprises means for blocking the assembly carrying the rod 28 relative to the injector body 12 and control means of the control means. blocking for selectively controlling the locking means as a function of the speed of movement of the assembly 28 carrying the rod 24.
• the locking means of the assembly 28 carrying the rod 24 relative to the body of the injector 12 comprise a piston 54 slidably mounted in a cylinder 56, the piston 54 and the cylinder 56 defining a blocking chamber 58.
• the piston 54 is integral with the active assembly 28 and is able to slide inside the cylinder 56 formed, in this case, by the inside of the body. Injector 12.
• the blocking chamber 58 is in fluid communication with the cavity 18.
• this fluid communication between the blocking chamber 58 and the second upper cavity 18 is achieved by means of a small clearance between the piston. 54 and the interior of the injector body 12.
• the fluid communication between the blocking chamber 58 and the interior of the cavity 18 is achieved by means of a duct 60 of small section of pass ge.
• the blocking chamber 58 is also in fluid communication with the outside of the injector 52 by means of the discharge duct 32 of small section.
• the evacuation of the low pressure fuel contained in the second upper cavity 18 can only be achieved through the duct 60, the blocking chamber 58 and the exhaust duct 32.
• the active assembly 28 controls:
• the spring 30 tends to oppose the lifting of the closure head 26 of the injection port 23.
• the spring 30 thus tends to move the active assembly 28 which carries the rod 24 at a relatively high speed .
• the piston 54 tends to be driven at high speed also, the piston 54 being integral with the active assembly 28.
• the piston 54 tends to move so as to modify the volume of the blocking chamber 58, in this case so as to reduce the volume of this blocking chamber 58.
• the emptying of the blocking chamber 58 in fuel can be achieved through the conduit 60 and / or the exhaust duct 32 which are of small section.
• a rapid movement of fuel between the blocking chamber 58 on the one hand, and the second cavity 18 and / or the outside of the injector, on the other hand, is prevented because of its viscosity.
• the fuel contained in the blocking chamber 58 exerts a force on the piston 54 which opposes the movement of the piston 54 printed by the spring 30.
• the blocking chamber 58, the cylinder 56 and the piston 54 act as locking means for the active assembly 28 carrying the rod 24.
• the spring 30 also acts on the active assembly 28, between the injection phases, to compensate for the differential expansions.
• the fuel contained in the hydraulic blocking chamber 58 can be evacuated through the discharge pipe 32 and / or the first pipe 60 with a low flow rate, which nevertheless allows sufficient movement of the rod
• the rod 24 is moved at a reduced speed, so that the action of the spring 30 is not prevented by the blocking chamber 58, the piston 54 and the cylinder 56.
• the first duct 60 and the exhaust duct 32 thus form control means for the blocking means formed by the blocking chamber 58, the piston 54 and the cylinder 56, the control means selectively controlling the blocking means as a function of the speed of movement of the active assembly 28.
• FIG. 4 which shows an injector 62 according to a second embodiment of the invention
• the injector 62 is also an outgoing needle injector.
• This injector 62 has two differences with respect to the injector 52 according to the first embodiment of the invention:
• the assembly 28 carrying the rod 24 comprises a mass for performing an acoustic impedance break, which replaces the active assembly as described in the context of the first embodiment of the invention.
• this injector 62 does not differ significantly from the operating mode of the injector 52 according to the first embodiment of the invention.
• FIG 5 shows a detail 68 of a third embodiment of the injector according to the invention.
• This third embodiment of the invention is distinguished from the first two modes described with reference to Figures 3 and 4 in that it has check valves 70, 72 mounted in the blocking chamber 58 so as to selectively close the first conduit 60 and exhaust conduit 32, respectively. Thanks to these nonreturn valves 70, 72, the first filling with fuel of the blocking chamber 58, prior to any commissioning of the injector according to the third embodiment of the invention, is carried out more fast compared to the first two embodiments described with reference to Figures 3 and 4.
• the non-return valve 72 for selectively closing off the exhaust duct 32 is preformed in the "up" position, as shown in FIG. 5, so that its free end moves away from the wall. non-return valve support, even when it is in the closed position. In this way, the non-return valve 72 allows a low fuel leakage from the blocking chamber 58 in the exhaust duct 32.
• FIG. 6 shows a detail 74 of an injector according to a fourth embodiment of the invention.
• the cylinder 56 integral with the injector body 12, is formed in the plug 33 closing the second upper cavity 18 formed in the injector body 12.
• the first conduit 60 allowing the fluid communication between the blocking chamber 58 and the second upper cavity 18, is formed in the piston 54. Furthermore, the blocking chamber 58 is in fluid communication with the outside of the injector body 12 by means of an evacuation duct of the chamber 76 separate from the evacuation duct 32 which puts in fluid communication the second upper cavity 18 directly with the outside of the injector body 12.
• non-return valves 70, 72 are mounted to the inside the blocking chamber 58 so as to selectively close off the fluid communication between the blocking chamber 58 and the second upper cavity 18, or the outside of the injector body 12, respectively.
• the operation of this injector according to the fourth embodiment of the invention is identical to the operation of the injector, a detail of which is shown in FIG.
• the blocking chamber 58 is in fluid communication with the outside of the injector body 12 by means of an exhaust duct of the chamber 76 separate from the exhaust duct 32 of the second upper cavity 18, a better evacuation of the fuel present in the second upper cavity is obtained by means of a discharge duct 32 of larger passage section. This advantageously avoids any rise in pressure in the second upper cavity 18 which could damage the injector 74 according to the invention or degrade the operation.
• the injector 74 according to the fourth embodiment of the invention which can be combined:
• the injector does not have a non-return valve 70, 72 able to close off the first duct and the evacuation duct of the chamber, respectively;
• the first duct 60 is pierced in the plug 33 of the injector; the blocking chamber 58 and the first duct 60 initially contain a fat soluble in the fuel, so as to avoid the formation of air bubbles in the blocking chamber 58 and / or in the first duct 60.
• FIG. 7 shows a detail 78 of an injector according to a fifth embodiment of the invention.
• the injector according to the fifth embodiment of the invention differs from the prior art in that it comprises means locking the assembly carrying the rod relative to the body of the injector and control means of the locking means for selectively controlling the locking means as a function of the speed of movement of the assembly carrying the rod.
• the locking means comprise a piston 54 fixed relative to the injector body 12 of the injector and a cylinder 56 integral with the assembly carrying the rod.
• the piston is fixed relative to the injector body because it has a projection 80 embedded in the plug 33 of the injector body 12.
• the blocking means further comprise a second chamber 82 whose function, filled with viscous fluid, to slow down or block the movement of the assembly 28 bearing the rod 24 towards the injection port of the injector according to the fifth embodiment of the invention.
• This second blocking chamber 82 is delimited by the piston 54, and is opposed in the cylinder 56 to the first blocking chamber 58 with respect to the piston 54.
• the first blocking chamber 58 is in fluid communication with the interior of the second cavity 18 by means of a first conduit 60 of small passage section.
• the second blocking chamber 82 is in fluid communication with the second upper cavity 18 by means of a second conduit 84 of small passage section.
• the first and second conduits 60, 84 have a passage section sufficiently reduced so as to achieve a significant pressure drop.
• an exchange duct 86 is bored in the piston 54, so as to put in fluid communication the first and second blocking chambers 58, 82.
• a valve The non-return valve 70 is mounted within the first blocking chamber 58 to selectively seal the first conduit 60 and thereby cut off the fluid communication between the first blocking chamber 58 and the second top cavity 18.
• the second blocking chamber 82 is not in direct fluid communication with the second upper cavity 18 through a second conduit.
• the first conduit 60, the first blocking chamber 58, the exchange conduit 86 between the first and second blocking chambers 58, 82, and the second blocking chamber 82 are initially filled with soluble grease in the fuel.
• the exchange conduit 86 and / or the second conduit 84 are preferably made in the form of conduits which extend in a helix or at an angle to the axis YY 'of the injector.
• Figure 8 shows a detail 90 of an injector according to a sixth embodiment of the invention.
• the locking means comprise two locking chambers 58, 82 disposed on either side of the piston 54 secured to the body of the injector by means of a projection 80 embedded in the plug 33 of the injector. These two blocking chambers 58, 82 are in fluid communication by means of an exchange duct 86 of small passage section formed in the piston 54.
• the blocking chambers 58, 82 are not in fluid communication with the second upper cavity 18.
• the blocking chambers 58, 82 as well as the exchange conduit 86 are filled with a fat which may be insoluble in the fuel.
• the piston 54 has a second projection 92 opposite the first projection 80 of the piston 54 embedded in the plug 33 relative to the piston 54.
• the first and second projections 80, 92 are of substantially equal section.
• the surface S1 of the piston in contact with the grease contained in the first blocking chamber 58 is equal to the surface S2 of the piston 54 in contact with the grease contained in the second blocking chamber 82.
• the second projection 92 and the cylinder 56 delimit a chamber 94 in fluid communication with the second upper cavity 18 through a conduit 96 whose passage section is chosen so as to always allow fluid communication between the chamber 94 and the upper cavity 18 without the viscosity of the fuel contained in the chamber 94 and in the second upper cavity 18 does not cause resistance to the evacuation and / or filling of the chamber 94.
• the locking means have a substantially symmetrical operation in axial locking towards the plug of the body of the injector and towards the injection orifice. It is therefore possible to block the fast translation movements of the assembly carrying the rod towards the plug 33 as well as towards the injection orifice 23.
• the force exerted by the liquid or fat contained in the first blocking chamber and in the second blocking chamber is equivalent when the pressure in the two chambers is equal.
• the piston and the cylinder do not tend to move the assembly carrying the rod in a position away from the equilibrium position in which the spring 30 tends to maintain the assembly carrying the rod.
• the locking means comprise two locking chambers 58, 82 delimited by a piston 54 integral with the injector body 12 by means of a projection 80 embedded in the plug 33, and by a cylinder 56 integral in translation with the assembly carrying the rod.
• the control means of the locking means comprise an exchange duct 86 of small passage section, formed in the piston 54 and which allows the communication of fluid between the two locking chambers 58, 82.
• the blocking chambers 58, 82 are not in fluid communication with the second upper cavity 18.
• a duct 100 is formed in the projection 80 of the piston 54 which is embedded in the plug 33, this duct 100 opening on the one hand at the upper end 102 of the projection of the piston 80 flush with the outside of the plug 33, and, secondly, in the first chamber block 58.
• This duct 100 is formed of an axial section 100a, coaxial with the axis yy 'of the injector rod, partially filled with the same liquid as the second section 100b, the first blocking chamber 58, the second blocking chamber 82 and the exchange duct 86.
• a movable cap 104 is disposed inside this section 100a so as to compensate for the difference in volume displaced due to the different surfaces of the piston in contact with the first blocking chamber 58 and the second blocking chamber 82, respectively.
• this movable plug 104 is made of elastomeric material.
• the section 100a is plugged at its end flush with the plug 33 by means of a sealing plug 106. Between the sealing plug 106 and the movable plug 104 a volume of buffer air 108 is maintained so as to allow the plug to be displaced. moving elastomer 104.
• This embodiment of the invention is very advantageous because the piston and cylinder assembly can be made independently before being mounted in the injector.
• conduit 100 may according to a variant of this embodiment, not lead into the first blocking chamber 58, but into the second blocking chamber 82.
• the piston 54 has, as has been described with reference to FIG. 8, a second projection which extends through the second locking chamber and which delimits a third hydraulic chamber in fluid communication with the second upper cavity 18 inside the injector body 12.
• this second projection of the piston makes it possible to obtain that the surface of the piston in contact with the liquid contained in the first blocking chamber is substantially equal to the surface of the piston in contact with the fluid contained in the second blocking chamber 82.
• FIG. 10 shows a detail 1 10 of an injector according to an eighth embodiment of the invention.
• control means of the locking means comprise shutter means, in this case of the solenoid valve type 112, selectively activatable which are mounted in a single exhaust duct 32 of the blocking chamber 58. Thanks to these selectively activatable closing means of the exhaust duct 32, the means for blocking the assembly carrying the rod are controlled very effectively. This blocking can be controlled during the injection phases while the spring 30 acts on the assembly carrying the rod so as to tend to move this assembly carrying the rod at high speed.
• the closure means of the evacuation duct are made by means of a high magnetic permeability tube delimiting the evacuation duct, a solenoid surrounded around this tube. High magnetic permeability and a soft steel valve that is pressed against the tube when the solenoid is energized.
• an active device of the valve type can be arranged so as to close off the single exhaust duct 32 whatever the embodiment of the invention used, as long as it has a single evacuation duct. 32.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)

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• 2007
  • 2007-03-23 FR FR0702132A patent/FR2914024A1/fr active Pending
• 2008
  • 2008-03-25 WO PCT/FR2008/050507 patent/WO2008132399A2/fr active Application Filing
  • 2008-03-25 EP EP08788034A patent/EP2126334B1/de not_active Not-in-force

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